Ischaemic heart disease (including stable Phaeochromocytoma angina)

Overview

Differentiating the ischaemic syndromes
FeatureStable anginaUnstable anginaNSTEMI
OnsetExertional onlyRest, minimal exertion, or rapidly worseningRest, minimal exertion, or rapidly worsening
ReliefRest or GTN within 2-3 minMay not fully resolveMay not fully resolve
Serial troponinNormalNormalElevated
ECGNormal between episodesST depression / T-wave inversion or normalST depression / T-wave inversion

Feature	Stable angina	Unstable angina	NSTEMI
Onset	Exertional only	Rest, minimal exertion, or rapidly worsening	Rest, minimal exertion, or rapidly worsening
Relief	Rest or GTN within 2-3 min	May not fully resolve	May not fully resolve
Serial troponin	Normal	Normal	Elevated
ECG	Normal between episodes	ST depression / T-wave inversion or normal	ST depression / T-wave inversion

🎯
Unstable angina and NSTEMI are clinically identical - serial high-sensitivity troponin (0 h and 3 h) is the key differentiator. Elevated troponin = NSTEMI.

Investigations

🥇 First-line

•CT coronary angiogram (CTCA) - non-invasive, directly visualises coronary anatomy, identifies stenoses >50%; NICE-recommended first-line imaging for suspected CAD

•Resting 12-lead ECG - usually normal between episodes

•Blood tests - fasting lipid profile, HbA1c, FBC (exclude anaemia), TFTs, renal function

•Serial high-sensitivity troponin (0 h and 3 h) - to exclude NSTEMI if any doubt

🥈 Second-line

•functional imaging (myocardial perfusion scintigraphy, stress echo, cardiac MRI) - when CTCA non-diagnostic or functional significance of stenosis needs assessment

🏆 Gold standard

•invasive coronary angiography - reserved for high probability CAD likely to need PCI or CABG, or inconclusive non-invasive tests

⚠️
Exercise treadmill test is NO longer recommended as first-line for diagnosing stable angina (NICE 2016) - poor specificity, does not visualise anatomy, high false-positive rate especially in women.

Management

•Acute symptom relief: sublingual glyceryl trinitrate (GTN) spray - at symptom onset or prophylactically before exertion; if not relieved by two doses within 10-15 minutes, call 999

•First-line anti-anginal: beta-blocker (e.g. bisoprolol) OR long-acting dihydropyridine calcium-channel blocker (e.g. amlodipine)

•If monotherapy inadequate: add the other agent - combine beta-blocker + amlodipine (dihydropyridine CCB)

•If beta-blocker intolerant: use long-acting nitrate (isosorbide mononitrate) as alternative

🥉 Third-line

•long-acting nitrate if dual therapy fails

•Refer to cardiology for angiography if: symptoms persist on maximal medical therapy, ECG shows extensive ischaemia, or revascularisation (PCI/CABG) likely needed

🚨
Never combine verapamil or diltiazem (rate-limiting CCBs) with a beta-blocker - risk of severe bradycardia, complete heart block, and precipitation of heart failure. Amlodipine (dihydropyridine) is safe to use with a beta-blocker.

⚠️
Nitrates (GTN, long-acting nitrates) are absolutely contraindicated with PDE5 inhibitors (sildenafil, vardenafil - avoid for 24 h; tadalafil - avoid for 48 h). Combination causes profound refractory hypotension.

Prinzmetal (Variant) Angina

•Caused by coronary vasospasm (not fixed stenosis) - occurs at rest, typically early morning

•More common in younger patients and smokers

•ECG during episode shows ST elevation (not depression)

•Managed with nitrates and calcium-channel blockers; beta-blockers may worsen vasospasm

Presentation of Stable Angina

•Central chest pressure/heaviness - rarely sharp

•Radiation to left arm, jaw, or neck

•Triggered by exertion, cold, emotional stress, or heavy meals

•Relieved by rest within 1-5 minutes or sublingual GTN within 2-3 minutes

•Predictable and reproducible - same exertion level reliably triggers symptoms